This invention pertains to the field of floating boring bar cartridges. It more particularly pertains to the field of adjustable floating boring bar cartridges having indexable cutting inserts for use in broadnosing (or skiving) applications.
In the past, adjustable floating boring bar cartridges had two oppositely facing single cutting edge inserts, of a rectangular-like geometry, mounted in, and extending out of, the lateral faces of the cartridge. Movement of the cutting inserts outward to the desired final bore size is achieved by movement of a wedge-like adjusting plate, located within the cartridge and between the cutting inserts. The adjusting plate has two oppositely facing lateral sides which are inclined inwardly and forwardly. Each of these two inclined faces mates and abuts against a complimentary inclined face on the rear of each cutting insert.
The turning of an adjusting screw, which is joined to adjusting plate, pulls the plate forward, thus producing a wedging action which forces the cutting edge of each insert to further protrude from the lateral faces of the cartridge. Each insert is then locked in position by abutment with the end of a locking screw located above it.
This mechanism for adjusting the position of inserts does not readily facilitate inward adjustment. To achieve an inward adjustment, the adjusting plate is first moved to the rear of the cartridge, that is, out of abutment with the rear faces of the inserts. Next, the operator manually presses the inserts into abutment with the wedge-like member. At this point, the inserts are farther inward than actually desired. Adjustment to the final position is achieved as before, by wedging the inserts outwardly by moving the adjusting plate forward.
In addition to the above awkwardness in the adjustment of the inserts, the above cartridge design cannot be used with indexable cutting inserts. The use of indexable cutting inserts eliminates the need for resharpening of cutting edges as had been done with the above single edge inserts. Resharpening of a cutting edge offered an opportunity for introducing defects into the cutting edge which could cause the insert to fail during machining, possibly damaging the workpiece and/or the cartridge.